Many kinds of pipe couplings with clamping rings exist in the art. It is noted that throughout the specification and claims, the term “pipe” encompasses any kind of generally cylindrical object. For example, one large family of pipe couplings includes a cylindrical housing with a clamping ring at one end or both ends of the housing. The clamping ring has a seal in its inner contour. Tightening the clamping ring tightens the seal on the outer contour of a pipe.
One kind of clamping ring is a unitary ring, which may be made of cast iron or other suitable material. The ring is not a full ring but a partial ring with open upper ends that are tightened towards each other with bolts or other fasteners.
Another kind of clamping ring is a split clamping ring; the ring has two halves that are hinged together at the bottom of the ring opposite the open ends that are tightened together.
However, as opposed to continuous rings in which the forces on the ring are somewhat uniformly distributed, in split clamping rings the forces are different at the clamp ends and at the hinge ends and therebetween. The result is the forces may tend to cause the complete ring to depart from a true circular shape, and the seal or gasket may not seal properly around the entire circumference of the pipe. The hinge must bear higher forces, which makes the hinges generally heavier and thicker.